For decades, rodents have provided researchers with a tool for prediction biological risk in humans. With the emergence of new technologies in molecular genetics, it has been possible to both identify and manipulate genes involved in a variety of homeostatic mechanisms, and to engineer new models for the assessment of toxicological risk. The result of such efforts has been the addition of several new and exciting models to the toxicologist "toolbox." As biologists continue to identify new genes and struggle to understand their complex biological properties, the potential for new models continues to increase. In addition, the task of identifying the most informative and appropriate models becomes increasingly more difficult, both from scientific and regulatory standpoints. Therefore, the primary objectives of this meeting are: 1) to provide an overview of current models used in risk assessment; 2) to identify potential new models; 3) to examine genetic and epigenetic factors that need to be considered in developing new models; and 4) to highlight efforts to set up regulatory guidelines for the validation and acceptance of models in modern risk assessment. This meeting will provide a forum for the communication of recent advances in modeling and will allow young investigators an opportunity to interact with leaders in the field. The meeting will focus on models used to screen potential carcinogens, genotoxins and other xenobiotics posing potential health risks and will offer perspective as to future strategies in model development. Aspects of modeling theory and data interpretation will be incorporated into a program that will include round table discussion on genetic and environmental consideration in the development of effective models. This meeting will provide a novel opportunity to assemble a large concentration of investigators using genetic models in risk assessment, exchange ideas and map future directions in the field.